1. Field of the Invention
This invention relates to a coding arrangement including a pair of matched coding elements that are respectively connected between a pair of components, such as a terminal block and a printed circuit board, so that only authorized components can be electrically connected with each other. The invention also relates to a method for mounting the coding elements on their respective components.
2. Background of the Invention
Various coding arrangements are well known in the prior art. In the German patent No. DE 38 30 187, for example, there is disclosed a coding device for switchboard plug-in modules for the purpose of definite match up of plug-in modules and plug-in chambers with the help of coding projections on the module and coding devices corresponding therewith on the module support. The coding projections are attached on the underside of a module bottom, standing perpendicularly in a row at a right angle to the direction of insertion. On the bottom sheet metal piece of the module block, there is provided a coding plate with grooves located in the direction of insertion whose interval corresponds to the interval between the coding projections. The coding projections protrude into the grooves. Coding systems such as these entail the disadvantage that coding in practice is often dispensed with due to the effort connected with assembly. But this can lead to problems or damage, for instance, because various potentials, (for example, 24 V and 230 V) can be combined.
According to the prior art coding arrangement of FIG. 6, the problem arises that codings with few projections can be stuck into coding receptacles with free socket holes. For instance, pin xe2x80x9c1xe2x80x9d in FIG. 6 can be stuck not only in socket xe2x80x9c1xe2x80x9d but also into sockets xe2x80x9c3, 5, 7, 9, 11, 13, 15.xe2x80x9d This does not reliably rule out the possibility of making a mistake in sticking the pin in. The problem therefore is this, as FIG. 6 furthermore shows by way of example: If one has a total of four peg locations with one and three projections, then out of the theoretical 16, one can make only four coding variants that really differ from each other. If there are five peg positions, then there are ten genuine differentiation possibilities.
Starting with this state of the art, the present invention is intended to provide a simple coding system that is distinguished by high coding assurance and a large number of coding variants that can also be implemented in a narrow space. Another part of this problem involves ensuring the fact that the coding device can be assembled in an uncomplicated and quick manner.
The present invention was developed to avoid the above and other drawbacks of the known coding systems.
Accordingly, a primary object of the present invention is to provide a coding arrangement in which a pair of coding elements are connected between a pair of authorized components, such as a terminal block and a printed circuit board, whereby only the authorized pair of components can be displaced together toward a fully connected position.
According to a more specific object of the invention, the pair of coding elements each include a pair of angularly arranged coding surfaces each contained in a plane normal to the direction of connection of the components, the corresponding coding surfaces of the coding elements being parallel with each other. One of the coding elements includes a male projection or peg that extends in the direction of the other coding member and that carries one pair of angularly arranged coding surfaces. The corresponding pair of angularly arranged coding surfaces is formed either on projections on the other coding element, or on the walls of a non-circular female socket. The projections and/or sockets that can be assembled in each case essentially have a polygonal cross-section and form a part of a base surfacexe2x80x94in particular, a regular polygon or a non-circular surfacexe2x80x94on which they are aligned according to a coding system where the projections of the first and the projections and/or sockets of the second coding element in each case essentially rest with one of their outer sides against the circumference of the base surface and where, in case of different coding element variants, they rotate along the circumference of the base surface or are twisted with respect to each other. This coding system ensures a large number of coding variants so that any confusion can be eliminated. This is true, in particular, when two or more of these base surfaces or polygons are lined up directly along each other; one then gets a particularly large number of different reliably plugged-in coding variants in conjunction with the definite position match up (ensuring against twisting) of the components that are provided with the coding device; this can be done in a very tight space.
According to another object of the invention, the corresponding projections and/or sockets essentially have rectangular cross-section that amounts to about half the surface of the base surface that is made as a square area. It is furthermore practical when one of the longitudinal sides of the rectangular projections or sockets rests against one of the outer sides of the square area and/or when the surfaces of the different projection/projection or projection/socket combinations partly overlap each other. This coding system facilitates on a single square areaxe2x80x94with an edge that, for instance, amounts to only a few millimetersxe2x80x94the implementation of four different coding variants. The number of coding variants can be multiplied by lining up these square areas to receive the rectangular projections and sockets. In that way, with two areas lined up to each other in a narrow space, one can already implement 16 coding variants, and with three areas lined up next to each other in a row, one can make even 64 coding variants on a particularly narrow surface.
As another preferred embodiment that implements even more coding variants on one base surface, the base surface is made as a hexagon; the pegs are made as half-hexagonal surface or as a third of the hexagonal surface (135xe2x80x3 element) and the pins for various coding variants are offset with respect to each other along the outer circumference in 60xc2x0 steps. That idea can be carried forward with any number of hexagons; as the number of corners increases, one can, of course, theoretically increase the wide variety of coding variants on one base surface. But some time along the way, one encounters the problem of peg positions that will differ only very little from each other if the base surface is presumed to remain equally large.
The invention, moreover, solves another problem according to a particularly preferred embodiment. In electrical appliances, where in all units a uniform first component must be combined with a different second component, in other words, in electrical appliances that are built up on the basis of terminal blocks, which must be provided with different electronic housings, it so happens that storage is made more difficult by the coding devices, because for each electronic housing with the first coding element section, one must keep in stock a fitting terminal body with the corresponding second coding element section. To solve this problem, the two coding element sections can together be placed upon the first component and are so designed that when the two components are assembled, the second coding element section will so come to rest against the second component that upon separation of the two components from each other, the second coding element section will remain on the second component so that it forms a counterpart for the first coding element section that remains on the first component when the two components are separated from each other.
The present invention is particularly suitable for this embodiment, since the second coding element section that is attached to the base terminal unit is so made that when the housing is the set upon a base component, for example, the base terminal block, it will be retained in a recess in which it remains after removal of the housing from the base terminal block so that it forms the counterpart for the first coding element section that remains on the electronic housing upon the withdrawal of the electronic housing. In contrast to the prior art, this offers the following advantage: one of the two components, in particular, the base terminal units, during their production need not be provided with any coding device or with any of the coding element sections so that the storage of these components is considerably simplified. The electronics units of varying typesxe2x80x94for example, electronics units to implement communication between a first field bus and actors, initiators, etc.xe2x80x94on the other hand, are in each case provided with a differing, bipartite coding element; the second coding element section is xe2x80x9cput downxe2x80x9d upon the base terminal unit only when the electronic unit is first put on the base terminal unit. In case the electronic unit is exchanged later, the second coding element section remains on the base terminal unit and protects the electrical appliance that is made up of the base terminal units against inadvertent imposition of a xe2x80x9cfalsexe2x80x9d electronic unit with a coding that does not fit. This idea can be combined particularly advantageously with the invention-based coding system that can be made in a narrow space.
With regard to the second part of the problem that can also be contemplated independently, that is, to ensure that the coding device can be assembled in an uncomplicated and fast fashion, the invention solves the problem in the following manner: The two coding clement sections of each coding element are connected integrally via constrictions or rip-off edges with a flexible base unit, in particular, a handle upon which the two coding element sections can be assembled to form one coding element. The handle is preferably made as a plastic strap that can be bent by hand. The plastic strap is so dimensioned that the two coding element sections of the two coding elements that belong together can in each case be put together at the strap to form the coding element; therefore, one can reliably rule out any confusion during assembly. Besides, the handling is simple and one can prevent a situation where one must try to match up two mutually fitting elements during assembly. This high degree of safe assembly is further enhanced by a legend that is affixed upon the handle.
Another object of the invention is to provide a method for easily making the various coding devices of the coding system. For this purpose, one preferably provides a single mold with a number of recesses that corresponds to the number of coding variants to make the different variants of coding element sections so that all variants can be made in just one production cycle. The manufacturing process is further simplified in the following manner: For the various coding elements, different numbers of recesses are provided in the mold so as to corresponds to their frequency distribution. In a particularly preferred manner, the differing coding variants are assembled to form groups in the mold in keeping with the frequency arising from the particular purpose (for example, three groups: particularly frequently needed coding variants, normally frequent variants, rare variants). In this way, when one uses only one single tool, one can avoid the unnecessary production of variants that occur very infrequently.